Deodorizing system

ABSTRACT

The present invention relates to a deodorizing system for reducing the size of a facility and realizing the thermal efficiency much higher than the prior art, wherein a deodorizing furnace 1 is connected with thermal equipment 8 which uses a heated gas current as a heat source through an out-of-furnace circulating path 4 in order to circulate combustion exhaust gas in a deodorizing furnace 2 which has been used for incineration or thermal decomposition of odor components. When the combustion exhaust gas passes through a regenerative bed 5A or 5B on an intake side of the out-of-furnace circulating path, a part of sensible heat of the combustion exhaust gas is recovered in the regenerative bed 5A or 5B and the combustion exhaust gas is turned into a heated gas current that can be used in the thermal equipment 8 to be then supplied to the thermal equipment 8. Subsequently, upon completion of a predetermined process in the thermal equipment 8, the combustion exhaust gas is again made to have a high temperature and returned to the deodorizing furnace 2 by utilizing the recovered heat in the regenerative bed 5B or 5A on an outlet side of the out-of-furnace circulating path.

FIELD OF THE INVENTION

The present invention relates to a deodorizing system for removing odorsgenerated in a thermal equipment which utilizes a gas current having arelatively-medium/low temperature in a hot-air drier or a foaming ovenas a heat source to carry out a predetermined process.

BACKGROUND OF THE INVENTION

A deodorizing system such as shown in FIG. 5 has been conventionallyadopted in a process for removing gas (referred to as odor gas)including odor components generated in a foaming oven or a hot-air driersuch as a paint drying oven. The deodorizing system comprises: a hotblast stove 102 for supplying hot air having a medium/low temperature; athermal equipment 101 such as a hot-air drier or a foaming oven forutilizing hot air supplied from the hot blast stove 102 to effectpredetermined drying or foaming process on a work W; and a deodorizingfurnace 103 which takes out and burn or heat-decomposes the odor gasgenerated in the thermal equipment 101 for deodorization. Here, hot airhaving a medium/low temperature, e.g., approximately 300° C. required inthe thermal equipment 101 is generated in the hot blast stove 102, andatmosphere gas or flames having a high temperature, e.g., approximately1000° C. required for burning or heat-decomposing the odor gascomponents is formed in the deodorizing furnace 103.

The odor gas generated in a paint drying oven or a foaming oven,however, includes a large quantity of mist before deodorization and thismist is high-temperature gas including a large amount of carbonized dustafter deodorization, whereby heat recovery becomes difficult. Eventhough a heat exchanger is used to carry out heat recovery, the heatexchanger may soon be out of service and the heat efficiency is low.Thus, the high-temperature gas generated in the deodorizing furnace isnot subjected to the effective heat utilization and it is directlyexhausted. A difference in temperature between the heat required in thethermal equipment and the heat required for deodorization is not lessthan approximately 700° C., and hence a common heat source can not beused. Two different heat sources must be prepared for the hot blaststove and the deodorizing furnace, thereby taking a large space andincreasing the facility cost.

DISCLOSURE OF THE INVENTION

It is, therefore, an object of the present invention to provide adeodorizing system having a compact equipment and a thermal efficiencythat is much higher than that in the prior art.

To achieve this aim, the present invention provides a deodorizing systemfor removing odor components generated from a thermal equipment whichutilizes a gas current having a medium/low temperature as a heat source,comprising: a thermal equipment; a deodorizing furnace provided with aburner which mixes gas including the odor components emitted from thethermal equipment into a flame and burns it; and an out-of-furnacecirculating path which includes a circulating passage connected to thethermal equipment, a circulating fan and the deodorizing furnace througha pair of circulating openings, takes out combustion exhaust gas fromthe deodorizing furnace to the outside of the furnace through onecirculating opening and passes the combustion exhaust gas through thethermal equipment to flow back into the deodorizing furnace through theother circulating opening. Further, the out-of-furnace circulating pathcomprises regenerators provided to positions dose to the pair ofcirculating openings of the deodorizing furnace, respectively, and apassage switching device for periodically switching a direction of a gascurrent between the circulating fan and the regenerators. Burning theburner and changing over the passage switching device periodicallyswitch a direction of the gas current to the deodorizing furnace, andthe combustion exhaust gas taken out from the deodorizing furnace isturned into the hot air having a medium/low temperature required for thethermal equipment through the regenerators and it is then fed to thethermal equipment. Further, the recirculating gas including odorcomponents generated in the thermal equipment is again made to have ahigh temperature through the regenerators and flows back into thedeodorizing furnace for combustion.

According to this deodorizing system, when the combustion exhaust gas inthe deodorizing furnace having used for incinerating or thermallydecomposing the odor components passes through the regenerator on theintake side of the out-of-furnace circulating path, the sensible heat ofthe combustion exhaust gas is partially recovered by the regenerator sothat this gas be turned into the gas current having a medium/lowtemperature utilized in the thermal equipment and then supplied to thethermal equipment. Upon completing a predetermined operation in thethermal equipment, the gas is made to have a high temperature by usingthe recovered heat in the regenerator on the outlet side of theout-of-furnace circulating path and the gas is returned into thedeodorizing furnace. Therefore, of the heat generated in the deodorizingfurnace, the heat which can not be satisfactorily recovered by theregenerator and is wasted can be used as a heat source for the thermalequipment, thereby reducing the size of the facility and the costwithout requiring a separate hot blast stove for the thermal equipment.In addition, the heat wasted in the regenerator for obtaining the hotair having a medium/low temperature is again recovered and returned intothe deodorizing furnace when supplying the odor gas generated in thethermal equipment to the deodorizing furnace, and hence the deodorizingsystem which does not exhaust the heat unnecessarily and has a highthermal efficiency can be realized.

Furthermore, according to the deodorizing system of this invention,since the recirculating gas including the odor components which areflown back into the deodorizing furnace via the thermal equipment isagain made to have a high temperature through the regenerators, atemperature of the atmosphere gas in the deodorizing furnace can bereadily controlled by adjusting a quantity of an increase in heateffected by combustion of the burner, i.e., adjusting a quantity of fuelinjection. Moreover, the ignitionability and the stability of flames areimproved and the flames can not be blown out even though the oxygendensity is low and the flow velocity increases because the recirculatinggas is flown back at a high temperature and a temperature at theignition point can not be easily lowered. Also, the drying or foamingprocess in the thermal equipment consumes the heat of the recirculatinggas current, and hence the balanced temperature in the out-of-furnacecirculating path does not increase.

Here, adopting a pair of burners which alternately perform combustion asthe above-mentioned burner causes alternate combustion and therecirculating gas current whose direction periodically changes insynchronism with the alternate combustion in the deodorizing furnace toimprove the mixing of the gas in the deodorizing furnace and to smooth(average) the temperature in the deodorizing furnace. Further,incineration or thermal decomposition of the odor components can beefficiently performed in the wide area in the deodorizing furnace, andreduction in NOx can be also realized. Furthermore, according to thisdeodorizing system, since averaging the temperature in the deodorizingfurnace and improving the mixing state of the gas contribute to make thevolume ratio of the furnace space, which is effective for incinerationor thermal decomposition of the odor gas in the deodorizing furnace,larger than that of the prior art, reduction in the volume of thedeodorizing furnace or enhancement of the processing ability ispossible, thereby reducing the size of the deodorizing furnace.

Further, in the deodorizing system according to the present invention,the circulating opening is formed in the vicinity of the burner or ittakes the form of a burner throat of the burner. In this case, therecirculating gas current including the odor components generated in thethermal equipment is assuredly mixed in the flames, and hence combustionor thermal decomposition of the odor components can be attained in arelatively-small space. Therefore, the volume of the deodorizing furnacecan be reduced.

In addition, the circulating fan is provided between the regenerator andthe thermal equipment and on both the upstream side and the downstreamside of the thermal equipment, respectively, in the deodorizing systemaccording to the present invention. In such a case, gas circulationbetween the deodorizing furnace and the thermal equipment can berealized without being interfered with incursion of the air current intothe thermal equipment.

Moreover, the deodorizing system according to the present invention hasa circulation amount adjusting damper and a dust collector provided onthe upstream side of the thermal equipment in the out-of-furnacecirculating path. According to this deodorizing system, a requiredquantity of the recirculating gas is taken out from the deodorizingfurnace to the out-of-furnace circulating path in the thermal equipmentsuch as a hot-air drier oven or a foaming oven. Further, dust componentscontained in the recirculating gas are collected by the dust collectorbefore being led into the thermal equipment and then supplied as cleanhot air having a medium/low temperature. Thus, this does not adverselyinfluence operations performed in the thermal equipment, such as thedrying or foaming operation. Also, an appropriate quantity of the gascurrent required in the thermal equipment such as a hot-air drier or afoaming oven can be supplied by adjusting a quantity of therecirculating gas current.

Furthermore, the deodorizing system according to the present inventionprovides a bypass means for directly connecting the upstream and thedownstream of each regenerator in order that part or all of therecirculating gas bypasses the regenerator and flows into theout-of-furnace circulating path to enable temperature adjustment. Inthis case, changing allotment of the recirculating gas current passingthrough the regenerator and the counterpart bypassing through the bypassmeans can readily adjust a temperature of the recirculating gas to besupplied to the thermal equipment.

In addition, the deodorizing system according to the present inventionis provided with a mist capturing means at a position close to thethermal equipment of each regenerator, i.e., on the low-temperature sideof each regenerator. In this case, the mist carried by the exhaust fromthe thermal equipment is captured by the mist capturing means beforepassing through the regenerator and then dried to become dusts when therecirculating gas taken out from the deodorizing furnace passes throughthe regenerator. Accordingly, it is possible to prevent the mist fromentering in the deodorizing furnace and the recirculating gas can bekept clean by periodically disposing the dusts.

In the deodorizing system according to the present invention, it ispreferable to use a regenerative burner system provided withregenerators for alternately burning a pair of burners which supplycombustion air from the outside of the deodorizing furnace through theregenerators or exhaust combustion exhaust gas to the outside of thedeodorizing furnace. In this case, when exhausting the combustion gas,since its sensible heat is recovered in the regenerators and again usedfor preheating the combustion air with an extremely high thermalefficiency to be returned to the inside of the furnace, a temperature ofthe combustion air can be a high temperature close to a temperature ofthe combustion exhaust gas that flows out toward the regenerators, andthe high thermal efficiency can be maintained. Further, combustion ofthe burners is carried out by using the combustion air which does notrelate to the gas circulating between the deodorizing furnace and thethermal equipment, and the odor gas having a low oxygen density in theexhaust gas flowing back from the thermal equipment can be alsodeodorized.

In addition, in the deodorizing system according to the presentinvention, there may be provided a burner which has a fuel nozzle forblowing fuel in synchronism with changeover of a direction of the gascurrent and uses as the combustion air a part of the recirculating gasthat circulates the out-of-furnace circulating path and has an oxygendensity enough for maintaining stable combustion, and an exhaust meansfor exhausting gas that is generated by combustion and incurred air onthe upstream side of the thermal equipment. According to thisdeodorizing system, when the oxygen density of the gas flowing back fromthe thermal equipment is enough for maintaining stable combustionbecause of incurred air, fuel can be burned by only injecting a part ofthe recirculating gas from the circumference of the fuel nozzle.

Moreover, in this deodorizing system, it is preferable to provide a gascurrent restricting orifice and a throat so as to supply therecirculating gas having a range of optimum air ratio suitable for aquantity of fuel injection from the circumference of the fuel nozzle. Inthis case, a quantity of combustion in the deodorizing furnace can becontrolled by only adjusting fuel injection. According to thisinvention, a quantity of combustion in the deodorizing system can becontrolled by only adjusting a quantity of fuel injection because therecirculating gas having a range of optimum air ratio suitable for theinjection quantity is supplied from the circumference of the fuelnozzle.

Further, the deodorizing system according to the present inventioncomprises an air quantity adjusting damper and a regenerator, and thedeodorizing system may provide a pair of changeover regenerative burnersfor alternately burning a pair of burners which supply combustion airthrough the regenerator or exhaust combustion gas in synchronism withchangeover of a direction of the gas current and provide on the upstreamside of the thermal equipment an exhaust means for supplying ascombustion air the exhaust having an oxygen density that is exhaustedfrom the thermal equipment in the out-of-furnace circulating path on theupstream side of each air quantity adjusting damper and enough formaintaining stable combustion and for exhausting only combustiongenerated gas and incurred gas.

According to this deodorizing system, since the recirculating gascurrent having a predetermined temperature required in the thermalequipment can be obtained by the overall out-of-furnace circulating patheven though heat exchange is carried out with taking into account onlythe temperature efficiency in the regenerator of the regenerativeburner, the high thermal efficiency can be obtained, and alow-temperature damper can be used because the recirculating gas passingthrough the air quantity adjusting damper has a low temperature.

In any of the above-mentioned deodorizing systems according to thepresent invention, since only the combustion gas generated due to anincrease in heat and the air incurred into the thermal equipment areexhausted gas generated in the overall system and they are exhausted atan extremely low temperature, it is possible to attain the high thermalefficiency which can not be obtained in the prior art deodorizingsystem.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a preferred embodiment of a deodorizing system according tothe present invention and is a principle view of the deodorizing systemfor realizing deodorization of odor gas having a low oxygen density;

FIG. 2 is a principle view showing another embodiment of the deodorizingsystem according to the present invention;

FIG. 3 is a principle view showing still another embodiment of thedeodorizing system according to the present invention;

FIG. 4 is a vertical cross-sectional view showing an example of a mistcapturing means; and

FIG. 5 is a principle view showing an example of a prior art deodorizingsystem.

BEST MODES FOR EMBODYING THE INVENTION

The configuration of the present invention will now be describedhereunder in detail in conjunction with illustrative embodiments.

FIG. 1 shows an embodiment in which the present invention is applied toa preferred deodorizing system for deodorizing odor gas having a lowoxygen density. This deodorizing system is mainly composed of adeodorizing furnace 1 provided with at least a pair of burners 3A and 3Bwhich alternately perform combustion, an out-of-furnace circulating path4 for temporarily taking out combustion gas generated in the deodorizingfurnace 1 and again flowing it back from another position into thedeodorizing furnace 2, and a thermal equipment 8 constituting a part ofthe out-of-furnace circulating path 4 and using a gas current having amedium/low temperature as a heat source, and gas containing the odorgenerated in the thermal equipment 8 is burnt and removed in thedeodorizing furnace 1 by recirculating the gas current between thethermal equipment 8 and the deodorizing furnace 1.

The out-of-furnace circulating path 4 is provided with a pair ofcirculating openings 9A and 9B, regenerative beds 5A and 5B as a pair ofregenerators, circulating fans 6 and 10, a passage switching means 7 forselectively and alternately connecting the circulating fans 6 and 10with one of the regenerative beds 5A and 5B to switch a direction of aflow of a gas current toward the regenerative beds 5A and 5B, and athermal equipment 8 utilizing a gas current having a medium/lowtemperature as a heat source in order that a strong recirculatingcurrent (indicated by arrows) whose gas current direction isperiodically inverted in accordance with changeover of combustion of thepair of burners 3A and 3B of the deodorizing furnace 1 is formed in thedeodorizing furnace 2. Here, the strong recirculating current means arecirculating gas current having a volume much larger than that of thesupplied gas current.

The passage switching means 7 is positioned between the deodorizingfurnace 1 and an intake of the circulating fan 6 and between thedeodorizing furnace 1 and an outlet of the circulating fan 10 andprovided in such a manner that ducts 23A and 23B communicating with twocirculating openings 9A and 9B provided to the deodorizing furnace 1 beconnected to two (two ports provided at positions where these two portsdo not communicate with each other) out of four ports while the intakeof the circulating fan 6 and the outlet of the circulating fan 10 beconnected with the remaining two ports and that one of the circulatingopenings 9A and 9B be connected with the circulating fan 6 while theother be connected with the circulating fan 10. The circulating openings9A and 9B formed in the deodorizing furnace 2 of the out-of-furnacecirculating path 4 are arranged in the vicinity of respective burnerthroats of the burners 3A and 3B so that the recirculating gas currentflowing back from the thermal equipment 8 collides with flames andcombustion gas. It is to be noted that the passage switching means 7 isnot restricted to a four-way valve and it can be substituted by anyother passage switching means having the same function. In addition, thepassage switching means 7 is connected with a control four-way valve 12for alternately burning the pair of burners 3A and 3B by means of a linkor the like, and the passage switching means 7 and the four-way valve 12can be switched in synchronism with each other.

Further, the out-of-furnace circulating path 4, having the regenerativebeds 5A and 5B as the regenerators in the vicinity of the circulatingopenings 9A and 9B provided to the deodorizing furnace 1, recovers apart of sensitive heat of combustion exhaust gas taken out from thedeodorizing furnace 1 by the regenerative beds 5A and 5B and circulatesit after turning into a gas current having a medium/low temperaturesuitable for being used in the thermal equipment 8. Furthermore, itagain turns it into a high-temperature gas current by direct heating inthe regenerative beds 5A and 5B when flowing it back into thedeodorizing furnace 1. Here, either the intake side of the circulatingfan 6 or the outlet side of the circulating fan 10 is selectivelyconnected with the respective circulating openings 9A and 9B through thepassage switching means 7, and the combustion exhaust gas taken out fromthe deodorizing furnace 1 through one of the regenerative beds 5A and 5Bis supplied to the thermal equipment 8 while the exhaust containing odorgas generated in the thermal equipment, namely, the recirculating gas isflowed back to the deodorizing furnace 1. It is to be noted that acirculation quantity adjusting damper 18 for adjusting a quantity of therecirculating gas current and a dust collector 19 are provided betweenthe circulating fan 6 and the thermal equipment 8. Dusts and others areremoved and an appropriate quantity of the dean recirculating gascurrent is supplied to the thermal equipment 8. The circulation quantityadjusting damper 18 flows the medium/low-temperature combustion exhaustgas, i.e., the recirculating gas whose quantity is required in thethermal equipment 8. Further, a dust collector for a low temperaturesuch as a bag filter may be used as the dust collector 19.

Also, a furnace pressure adjusting damper 20 is provided between thethermal equipment 8 and the circulating fan 10. The furnace pressureadjusting damper 20 balances an exhausting quantity and a recirculatingquantity of the gas by maintaining the atmospheric pressure or apressure slightly-lower than the atmospheric pressure in the thermalequipment 8. This prevents the odor gas generated in the thermalequipment 8 from leaking outside the system. It is to be noted that thethermal equipment 8 uses the gas current having a medium/low temperatureas a heat source to apply a predetermined process such as a drying orfoaming process on the work W.

A bypass 21 is provided to each of the regenerative beds 5A and 5B ofthe out-of-furnace circulating path 4, and a temperature adjustingbypass damper 22 is disposed to the bypass 21. The temperature adjustingbypass damper 22 flows a part of the combustion exhaust gas, i.e., therecirculating gas taken out from the deodorizing furnace 1 to thepassage switching means 7 without passing through the regenerative beds5A and 5B and adjusts the recirculating gas to have a desiredtemperature by mixing the recirculating gas and the gas which has passedthrough the regenerative beds 5A and 5B.

Further, a regenerative burner system is adopted as a pair of burners 3Aand 3B attached to the deodorizing furnace 1 in this embodiment. Theregenerative burner system selectively and alternately connects the pairof burners 3A and 3B having regenerators which are regenerative beds 11Aand 11B to an air supply system 13 or an exhaust system 14 through apassage switching means 12 in order that one of the two burners 3A and3B performs combustion while the other which is not burning exhausts alarge part of combustion gas which has been used for combustion orthermal decomposition of odor components contained in the recirculatinggas. The respective burners 3A and 3B are provided on, e.g., the bothside walls of the deodorizing furnace 1 so as to be opposed to eachother and they alternately operate. Note that the burners 3A and 3B donot have to be separately arranged on the both side walls of thedeodorizing furnace 1 so as to be opposed to each other, and they may beprovided on, e.g., one wall of the deodorizing furnace 1 according tocircumstances. Incidentally, reference numeral 16 denotes a fuel nozzlein the drawing.

The regenerative beds 11A and 11B are accommodated in burner bodies,different casings or the like and incorporated in the burners 3A and 3B,respectively. The regenerative beds 11A and 11B perform heat exchangewith the combustion exhaust gas passing therethrough to recover thewasted heat and preheat the combustion air by using the recovered heat.The regenerative beds 11A and 11B of the respective burners 3A and 3Bare connected with two (two ports provided at position where they do notcommunicate with each other) out of four ports of the four-way valve 12through ducts 15. Further, an air supply system 13 and an exhaust system14 are connected with two remaining ports of the four-way valve 12. Asto the burners 3A and 3B and the regenerative beds 11A and 11B, oneburner and one regenerative bed are connected with the air supply system13 while the remaining burner and regenerative bed are connected withthe exhaust system 14, their connection can be switched by changing overthe four-way valve 12. Note that the four-way valve 12 and the passageswitching means 7 are changed over in synchronism with each other.

Here, it is preferable to use the structure and material whose pressureloss is relatively low but heat capacity is large and which have theimproved durability, e.g., a ceramic cylindrical body which has aplurality of cells and a honey-comb shape for the regenerative beds 11Aand 11B used in the burners 3A and 3B and the regenerative beds 5A and5B provided in the out-of-furnace circulating path 4. For example, ahoney-comb-shaped member manufactured by extrusion-molding the ceramicmaterial such as cordierite or mullite may be preferably used for heatexchange between a fluid having a high temperature of approximately1000° C. such as the combustion exhaust gas and a counterpart having arelatively-low temperature of approximately 20 through 200° C. such asthe combustion air or the odor gas. Further, as a honey-comb-shapedregenerative bed, it may be possible to employ a material other thanaluminum or ceramics, e.g., a metal such as a heat-resisting steel or acomplex of ceramics and a metal, e.g., an Al₂ O₃ --Al complex or anSiC--Al₂ O₃ --Al complex whose pores are completely filled up. This typeof complex can be manufactured by causing the melted metal tospontaneously penetrate into pores of the ceramics having a porousstructure, oxidating or nitriding a part of that metal to turn intoceramics. It is to be noted that the honey-comb shape essentiallyindicates hexagonal cells (holes) but it includes the structure havingsquare or triangular cells as well as hexagonal cells formed thereto inthis specification. In addition, the honey-comb-shaped regenerative bedmay be obtained by bundling tubes or the like without performingintegral molding. However, the shapes of the regenerative beds 5A, 5B,11A and 11B are not restricted to the honey-comb shapes, andflat-plate-type or corrugated-plate-type regenerative materials may beradially arranged in a cylindrical casing or pipe-like regenerativematerials may be filled in a cylindrical casing in such a manner thatthe fluid can pass through the materials in the axial direction.Further, a cylindrical casing in which two chambers are formed by apartition wall in the circumferential direction and the fluid can passin the axial direction may be prepared, and the regenerative bed may beconstituted by filling a lump of the spherical, short-pipe-like,short-rod-like, small-piece-type, nugget-type or net-type regenerativematerial in each of the chambers.

According to the deodorizing system having the above-mentionedarrangement, using only a heat source of the deodorizing furnace 1 canrealize operation of the thermal equipment 8 and deodorization of thegas containing the odor generated in the thermal equipment 8 in thefollowing manner.

A non-stationary flame is formed in the furnace 2 by alternately burningthe pair of burners 3A and 3B in the deodorizing furnace 1 in order toburn or thermally decompose the odor components in the recirculating gasflowing back from the thermal equipment 8 by using the combustion heat.Here, the burners 3A and 3B are switched in a short period of, e.g., notmore than 60 seconds, or more preferably, approximately 20 seconds or ashorter time. The changeover of combustion is performed by turningon/off injection of fuel and switching the four-way valve 12 for thecombustion air. The combustion air is preheated by the regenerative bed11A or 11B having heated by heat of the exhaust gas and comes to have anextremely-high temperature (for example, approximately 800 through 1000°C.). When the combustion air has such a high temperature, a temperatureof the mixed gas itself approximates to or becomes higher than atemperature of self ignition of the fuel even though the oxygen densityis low, and an increase in a response speed or a prominent extension ofcombustible limit largely contribute stability of combustion, resultingin the excellent combustion. Therefore, incineration or thermaldecomposition of the odor components is possible without hinderingcombustion even though the oxygen density of the recirculating gasflowing back from the thermal equipment 8 is low. Also, since therecirculating gas flowing back from the thermal equipment 8 comes tohave a high temperature by heat exchange performed between theregenerative beds 5A and 5B, a temperature at an ignition point is notextremely lowered even if the recirculating gas current collides with aflame 17, whereby the flame is not blown off.

Meanwhile, on the burner connected to the exhaust system 14, thecombustion gas which has been used for burning or thermally decomposingthe odor components is exhausted to the outside of the furnace throughthe burner throat. Here, the sensible heat of the exhaust gas isrecovered by the regenerative bed 11A or 11B in order that the exhaustgas has a low temperature, and the exhaust gas is then exhausted throughthe exhaust system 14.

At the same time, a part of the combustion gas is taken out to theout-of-furnace circulating path 4 through one of the circulatingopenings 9A and 9B as the recirculating gas and used as a heat source ofthe thermal equipment 8. Thereafter, it is again flowed back from theremaining circulating opening 9A or 9B to the deodorizing furnace 1.That is, a part of the atmosphere gas in the deodorizing furnace 2circulates between the deodorizing furnace 1 and the thermal equipment 8via the out-of-furnace circulating path 4. For example, in the stateshown in FIG. 1, the combustion gas in the deodorizing furnace 2 istaken out to the out-of-furnace circulating path 4 through theregenerative bed 5B of the circulating opening 9B by a negative pressuregenerated by the circulating fan 6. In this process, a part of thesensible heat of the recirculating gas current is wasted in theregenerative bed 5B and the recirculating gas current comes to have adesired temperature in order that this current can be used in thethermal equipment 8. Here, the full quantity of the recirculating gascurrent does not necessarily pass through the regenerative bed 5B and apart of the recirculating gas current passes through the temperatureadjusting bypass damper 22 if necessary. The recirculating gas currentwhich has passed through the regenerative bed 5B on the downstream sidethereof so as to have a low temperature is mixed with the recirculatinggas current which has bypassed the regenerative bed 5B to maintain ahigh temperature in order to generate the recirculating gas having atemperature (medium/low temperature) required in the thermal equipment8. For example, the combustion exhaust gas having a temperature of 800°C. is taken out from the deodorizing furnace 1 to generate therecirculating gas current having a temperature of 300° C. Thisrecirculating gas current is led into the thermal equipment 8 via thepassage switching means 7, the circulating fan 6, the circulationquantity adjusting damper 18 and the duct collector 19 in the mentionedorder. This recirculating gas current is then used for a predeterminedprocess such as a drying or foaming process.

The recirculating gas current having been used for the operation in thethermal equipment 8 is taken out from the thermal equipment 8 by aninduced draft fan 10, passes through the furnace pressure adjustingdamper 20 and the passage switching means 7 in the mentioned order, andflows back from the circulating opening 9A of the burner 3A performingcombustion into the deodorizing furnace 1. Here, the recirculating gascurrent is heated by the regenerative bed 5A to again have a hightemperature and flowed back into the deodorizing furnace 1. For example,even if a temperature of the recirculating gas current is lowered toapproximately 200° C. when it is taken out from the thermal equipment 8,the recirculating gas current is heated to have a temperature ofapproximately 700° C. by passing through the regenerative bed 5A so thatthis gas current be returned into the deodorizing furnace 1 assumingthat the air or the like entered into the thermal equipment 8 can beignored.

As mentioned above, since the deodorizing system according to thepresent invention recovers a part of the sensible heat of the gas in thedeodorizing furnace by the regenerative beds 5A and 5B to generate a gascurrent having a medium/low temperature which can be used in the thermalequipment 8 and returns the recirculating gas containing the odorcomponents exhausted from the thermal equipment 8 into the deodorizingfurnace 1 after turning the recirculating gas into a high-temperaturegas again by utilizing the recovered heat, the temperature can not belargely lowered even though the recirculating gas containing the odor ismixed with the combustion gas or the flame, and the non-stationary flamegenerated due to alternate combustion contributes to make thetemperature distribution in the furnace uniform, thereby attainingincineration or thermal decomposition of the odor components in a shorttime. Further, occurrence of no local high-temperature area reduces NOxto be generated.

It is to be noted that the above has described a preferred embodiment ofthe present invention, but the invention is not restricted thereto andvarious modifications or other embodiments are possible within a truescope and spirit of the invention. For example, description has beengiven as to the invention applied to the regenerative burner system,i.e., a heat source which uses the combustion air different from the gascirculating in the out-of-furnace circulating path 4 to alternately burnthe pair of burners 3A and 3B in the foregoing embodiment. However, thepresent invention is not restricted to the above application, and anyother regenerative burner or an usual burner such as shown in FIGS. 2and 3 may be used, for example.

FIG. 2 shows another embodiment of a deodorizing system which ispreferable to exhaust the gas which contains the odor components and hasa high oxygen density from the thermal equipment, for example. Thisexample has a configuration such that burner throats 25A and 25B of apair of regenerative burners 3A and 3B which alternately performcombustion are connected with ducts 23A and 23B of the regenerative beds5A and 5B of the out-of-furnace circulating path 4 on the downstreamside through ducts 26A and 26B so that a part of the recirculating gascurrent be supplied to the burners 3A and 3B and utilized as thecombustion air. Only the fresh air entering into the thermal equipment 8is supplied as the combustion air. The burner throats 25A and 25B of theregenerative burners 3A and 3B are connected with the out-of-furnacecirculating path 4 through the ducts 26A and 26B on the downstream sideof the regenerative beds 5A and 5B. In addition, air quantity adjustingdampers 27 for adjusting a quantity of the combustion air are providedto the connecting ducts 26A and 26B. Moreover, the exhaust system 29 isconnected on the upstream side of the thermal equipment 8, or morepreferably, between the downstream side of the dust collector 19 and thethermal equipment 8 through the exhaust adjusting damper 28, and a partof the recirculating gas current, i.e., the increased air generated bycombustion and the incurrent air are wasted as the excessive air. Therecirculating gas including the combustion gas which has been used forincineration or thermal decomposition of the odor components in thedeodorizing furnace 1 is partially subjected to heat recovery in theregenerative bed 11A or 11B of either the burner 3A or 3B which is notcurrently performing combustion and then led to the downstream side ofthe regenerative bed 5A or 5B of the out-of-furnace circulating path 4.At the same time, the combustion gas is partially taken out to theout-of-furnace circulating path 4 through the circulating opening 9A or9B and passes through the regenerative bed 5A or 5B where the combustiongas is cooled down to have a predetermined temperature. This gas isthereafter supplied to the thermal equipment 8. It is then used as aheat source of the thermal equipment 8 and flowed back to thedeodorizing furnace 1 again. In other words, the combustion exhaust gascontaining the recirculating gas circulates between the deodorizingfurnace 1 and the thermal equipment 8 through the out-of-furnacecirculating path 4, meanwhile the burners 3A and 3B of the deodorizingfurnace 1 alternately carry out combustion.

According to the deodorizing system having the above-mentionedarrangement, a part of the combustion gas in the deodorizing furnace 2passes through the regenerative bed 11B of the burner 3B which is notcurrently performing combustion and taken out to the out-of-furnacecirculating path 4 and the remaining part of the same is taken out tothe out-of-furnace circulating path 4 via the regenerative bed 5B of thecirculating opening 9B in the state shown in FIG. 2. During thisprocess, the sensible heat of the recirculating gas is partiallyrecovered in the respective regenerative beds 11B and 5B to obtain adesired temperature which can be used in the thermal equipment 8. Here,the recirculating gas current partially passes through the temperatureadjusting bypass damper 21 if necessary. The recirculating gas which haspassed through the regenerative beds 5B and 11B on the downstream sideof the regenerative bed 5B to have a low temperature is mixed with therecirculating gas which has bypassed the regenerative bed 5B to maintaina high temperature in order to generate the recirculating gas currenthaving a desired temperature. This recirculating gas current is led intothe thermal equipment 8 through the passage switching means 7, thecirculating fan 6, the circulation quantity adjusting damper 18 and thedust collector 19 in the mentioned order. The recirculating gas currentis then used for a predetermined process such as a drying or foamingprocess in the thermal equipment 8. The recirculating gas which has beenused for the operation in the thermal equipment 8 is taken out from thethermal equipment 8 by the induced draft fan 10 and passes through thefurnace pressure adjusting damper 20 and the passage switching means 7in the mentioned order. A part of the recirculating gas is then adjustedto have a desired air quantity and supplied from the duct 26Acommunicating with the burner throat 25A of the burner 3A which isperforming combustion so as to be used as the combustion air. Further,the remaining part of the same passes through the regenerative bed 5A toagain have a high temperature and then flows back from the circulatingopening 9A to the deodorizing furnace 2. In this deodorizing system,since the air quantity adjusting means, i.e., the both dampers 27 and 18are provided at positions where a temperature of the recirculating gascurrent is low, a general low-temperature damper can be used. Inparticular, even if the air quantity adjusting damper 27 positioned ineach of the ducts 26A and 26B is used and a temperature obtained by heatrecovery in the regenerative beds 11A and 11B is set lower than thatrequired in the thermal equipment 8 with taking into account only thetemperature efficiency, the recirculating gas is mixed with thecounterpart having a higher temperature on the downstream side in asubsequent process. Therefore, the recirculating gas current having apredetermined temperature required in the thermal equipment 8 can beobtained in the overall out-of-furnace circulating path.

Further, when exhausting the gas which contains the odor gas componentsand has a high oxygen density from the thermal equipment 8, adeodorizing system such as shown in FIG. 3 can be also embodied. In thisembodiment, regular burners 3A' and 3B' having no regenerative bedattached thereto are used as the burners and burner throats 25A' and25B' are connected with the upstream sides of the regenerative beds 5Aand 5B of the out-of-furnace circulating path 4 through ducts 30A and30B in order to supply a part of the recirculating gas current to theburners 3A' and 3B' as the combustion air. Only the fresh air enteringinto the thermal equipment 8 is supplied as the combustion air. Theburner throats 25A' and 25B' of the burners 3A' and 3B' are connectedwith the respective ducts 23A and 23B of the out-of-furnace circulatingpath 4 on the upstream sides of the regenerative beds 5A and 5B,respectively. Further, combustion air restricting orifices 31 foradjusting a quantity of the combustion air are provided to theconnecting ducts 30A and 30B, respectively. Moreover, the exhaust system29 is connected on the upstream side of the thermal equipment 8, or morepreferably between the downstream side of the dust collector 19 and thethermal equipment 8 through the exhaust adjusting damper 28, and theincreased quantity of the recirculating gas, i.e., the combustion gasgenerated from combustion and the air entering into the thermalequipment 8 are wasted as the excessive gas.

According to the deodorizing system having the above-mentionedarrangement, the combustion gas in the deodorizing furnace 2 is takenout to the out-of-furnace circulating path 4 through the circulatingopening 9B and the burner throat 25B' of the burner 3B' which is notcurrently performing combustion and circulates in the state shown inFIG. 3. During this process, the sensible heat of the combustion gas ispartially recovered in the regenerative bed 5B to have a desiredtemperature which can be used in the thermal equipment 8. Therecirculating gas which has been used for a predetermined process suchas a drying or foaming process in the thermal equipment 8 is taken outfrom the thermal equipment 8 by the induced draft fan 10 and heated bythe regenerative bed 5A to again have a high temperature. A part of thisgas is then flowed back from the circulating opening 9A into thedeodorizing furnace 2 and the remaining part of the same is supplied tothe burner throat 25A' through the duct 30A and the orifice 31 as thecombustion air to burn the fuel injected from the fuel nozzle 16.Injection of the fuel and the air is switched at predetermined timeintervals for alternate combustion of the burners 3A' and 3B'.

Further, the gas flowing out from the deodorizing furnace 1 or thethermal equipment 8 such as a foaming oven is dirty gas containing alarge amount of mist, and hence the mist should be removed. As acountermeasure, it is preferable to provide a mist capturing means 24such as shown in FIG. 4 on the downstream sides of the regenerative beds5A and 5B of the respective deodorizing systems, e.g., at positionsindicated by broken lines in FIGS. 1 through 3. The mist capturing means24 comprises an air-permeable case 32 such as a punching metal casewhich can be put into and removed from the ducts 23A and 23Bconstituting the out-of-furnace circulating path 4 in a direction acrossa flow of the recirculating gas current without restraint and anair-permeable filling 33 such as metal chips accommodated in the case32, for example.

When the mist capturing means 24 is provided on a position which isclose to the thermal equipment 8 of each of the regenerative beds 5A and5B and where the relatively-low-temperature gas flows, the mist in thegas can be attracted to the air-permeable filling 33 and removed whenthe non-deodorized recirculating gas including the odor components fromthe thermal equipment 8 passes through such a means. The mist capturedby the mist capturing means 24 is dried and turned into dusts when thedeodorized dry gas, i.e., the recirculating gas supplied from thedeodorizing furnace 1 passes by switching the flow direction of the gascurrent. Repeating this process in accordance with periodical changeoverof the flow of the gas current causes the dusts to be deposited to themist capturing means 24. It is enough to periodically take out the case32 from the ducts 23A and 23B and clean the filling 33.

In addition, although the above has mainly described the respectiveembodiments in which a combination of a pair of regenerative burnerswhich alternately perform combustion is adopted as a heat source, thepresent invention is not restricted to this structure, and one burnermay continuously effect combustion. In this case, it is preferable toarrange the burner so as to blow the recirculating gas injected from thepair of circulating openings 9A and 9B to the flame. Further, a heatsource such as a radiant tube burner may be employed.

What is claimed is:
 1. A deodorizing system for removing odor componentsgenerated from thermal equipment using a gas current as a heat source,comprising:thermal equipment; a deodorizing furnace provided with aburner and a pair of circulating openings; and an out-of-furnacecirculating path, which includes a circulating passage connected withthe thermal equipment, and a circulating fan, the circulating path beingconnected to the deodorizing furnace through the pair of circulatingopenings; the out-of-furnace circulating path taking out combustionexhaust gas from the deodorizing furnace to the outside of the furnacethrough one of the circulating openings and flowing back the combustionexhaust gas into the deodorizing furnace through the other circulatingopening after passing the combustion exhaust gas through the thermalequipment; and the out-of-furnace circulating path having regeneratorsprovided at positions adjacent the pair of circulating openings of thedeodorizing furnace, the circulating fan and a passage switchingapparatus periodically switching and inverting a direction of a gascurrent between the circulating fan and the regenerators, whereinchanging over the passage switching apparatus causes a direction of thegas current to the deodorizing furnace to be periodically inverted;combustion exhaust gas taken out from the deodorizing furnace beingheated to a temperature required in the thermal equipment through theregenerators and then supplied to the thermal equipment; andrecirculating gas containing odor components generated in the thermalequipment being heated in the regenerators and then flowing back intothe deodorizing furnace for combustion.
 2. The deodorizing systemaccording to claim 1, wherein the burner is of a regenerative burnersystem which alternately burns a pair of burners provided withregenerators in synchronism with changeover of a direction of a gascurrent, the pair of burners supplying combustion air from the outsideof the deodorizing furnace or exhausting combustion exhaust gas to theoutside of the deodorizing furnace through the regenerators.
 3. Thedeodorizing system according to claim 1, wherein there are provided apair of changeover regenerative burners which, in synchronism withchangeover of a direction of a gas current, alternately burn a pair ofburners, having air quantity adjusting dampers and regenerators, whichsupply combustion air or exhaust combustion exhaust gas through theregenerators, and on the upstream side of the thermal equipment isprovided an exhaust means which supplies as combustion air exhaust thatis exhausted from the thermal equipment of the out-of-furnacecirculating path on the upstream side of each air quantity adjustingdamper and has an oxygen density with which stable combustion can bemaintained and exhausts only gas generated by combustion and penetratedair.
 4. The deodorizing system according to claim 1, wherein thedeodorizing system provides: a burner which has a fuel nozzle forblowing fuel in synchronism with changeover of a direction of a gascurrent and uses as combustion air a part of recirculating gas currentthat circulates along the out-of-furnace circulating path and has anoxygen density with which stable combustion can be maintained; and anexhaust means for exhausting only gas generated by combustion andincurred air on the upstream side of the thermal equipment.
 5. Thedeodorizing system according to claim 4, wherein a gas currentrestricting orifice and a throat are provided in order to supply therecirculating gas current having an appropriate air ratio suitable to aninjection quantity of fuel from the circumference of the fuel nozzle. 6.The deodorizing system according to claim 1, wherein the circulating fanis provided on each of the upstream side and the downstream side of thethermal equipment between the regenerators and the thermal equipment. 7.The deodorizing system according to claim 1, wherein a circulationquantity adjusting damper and a dust collector are arranged on theupstream side of the thermal equipment in the out-of-furnace circulatingpath.
 8. The deodorizing system according to claim 1, wherein a bypassmeans for directly connecting the upstream and the downstream of eachregenerator is provided in order to enable temperature adjustment bycausing a part or all of the recirculating gas current to bypass theregenerator to flow through the out-of-furnace circulating path.
 9. Thedeodorizing system according to claim 1, wherein a mist capturing meansis provided to the thermal equipment of each regenerator.
 10. Thedeodorizing system according to claim 1, wherein the circulating openingis formed in the vicinity of the burner.
 11. The deodorizing systemaccording to claim 1, wherein the burner is a pair of burners whichalternately perform combustion and the circulating opening is a burnerthroat of the burner.